A pre-ablative thyroid-stimulating hormone with 30-70 mIU/L achieves better response to initial radioiodine remnant ablation in differentiated thyroid carcinoma patients.

Our aim was to clarify the optimum pre-ablative thyroid-stimulating hormone (TSH) level for initial radioiodine remnant ablation (RRA) in patients with differentiated thyroid carcinoma (DTC). From December 2015 to May 2019, 689 patients undergone RRA at Nuclear Medicine Department, Second Hospital of Shandong University were included in the study. Patients were categorized by their pre-ablative TSH level grouping of < 30, 30-70 and ≥ 70 mIU/L. Response to RRA were evaluated as complete response (including excellent and indeterminate response) and incomplete response (including biochemical and structural incomplete response) after a follow-up of 6-8 months. Multivariable binary logistic regression model was used to explore the optimum pre-ablative TSH level range and independent factors associated with response to RRA. Rates of complete response to RRA were 63.04%, 74.59% and 66.41% in TSH level groups of < 30, 30-70 and ≥ 70 mIU/L, separately. With multivariate analysis, the study found that pre-ablative TSH levels, gender and lymph node dissection were independent predictors of response to RRA. TSH between 30 and 70 mIU/L had a higher rate of complete response compared with TSH < 30 mIU/L, OR 0.451 (95% CI 0.215-0.958, P = 0.036). A pre-ablative TSH level of 30-70 mIU/L was appropriate for patients with DTC to achieve a better response to RRA.